Mounted fuel tank heater

ABSTRACT

A system (10) for preheating fuel in a fuel tank (16) for an internal combustion engine. The system (10) includes a heat exchanger (12) for transferring heat from a heated fluid to the fuel. The heat exchanger (12) includes a fuel tube (32) which is surrounded by the heated fluid for further heating of the fuel prior to its entering the fuel line of the vehicle or other device in which the system is installed. In the preferred embodiment, the heat exchanger (12) is installed through an access opening (14) normally provided in fuel tanks used in diesel engine-powered over-the-road trucks. A flange (18) is provided for securing the heat exchanger (12) to the flange (20) which surrounds the opening (14) in the fuel tank (16).

TECHNICAL FIELD

This invention relates to a system for preheating fuel for an internalcombustion engine in the fuel tank normally provided with a vehicle orother machine powered by such engine.

BACKGROUND ART

It is well known that preheating the fuel used in an internal combustionengine improves the efficiency of the engine. Further, preheating thefuel typically used in a diesel engine can avoid serious fuel flowproblems well known to occur in cold weather environments.

Diesel fuel, and in particular the No. 2 fuel oil typically burned bythe engines of over-the-road trucks, can congeal or "wax" in the coldweather regularly experienced during the winter months in the northernstates of the United States and in Canada. The jelling or waxing of fuelcan shut a diesel engine down, necessitating the towing of the vehicleto a repair facility where the fuel tank must be heated to alleviate theproblem. The expense of towing and downtime can be substantial.

A number of methods and devices have been developed in an attempt tosolve the problem of congealing fuel oil in cold weather. One method hasbeen to install a heater in the fuel line. U.S. Pat. No. 3,929,187discloses a device which utilizes this method. However, this method doesnot solve the problem of fuel oil congealing within the fuel tank itselfbefore it even gets into the fuel line. Another method is to install aheater in the fuel tank. U.S. Pat. No. 4,237,850 discloses a devicewhich utilizes this second method. The device disclosed in this patenthas two primary disadvantages. One, while the fuel can be heated in thetank to a temperature above that at which it "waxes", it is notnecessarily heated to a temperature which will prevent it fromcongealing in the fuel line in extremely cold weather, because of thevolume of fuel which must be heated in the tank which is usuallydirectly exposed to the cold outside air temperatures. Second, thedevice disclosed in this patent requires an access opening which must becut/formed into the top of the fuel tank prior to installation of thedevice.

Therefore, it is a principal object of the present invention to providea system for preheating diesel fuel in the fuel tank to a temperatureabove that at which the fuel would normally congeal.

It is a further object of the present invention to provide a system forpreheating the diesel fuel leaving the fuel tank to a temperature whichis sufficiently higher than the temperature at which the fuel wouldnormally congeal such that the fuel cannot jell in the fuel line betweenthe fuel tank and the diesel engine to which it is supplied.

It is yet another object of the present invention to provide a systemfor preheating the fuel in the fuel tank of a diesel engine-poweredvehicle or machine which includes a heat exchanger which can beinstalled through and secured in the opening normally provided in such afuel tank for the installation of a fuel level gauge.

DISCLOSURE OF THE INVENTION

Other objects and advantages will be accomplished by the presentinvention which provides a system for preheating fuel for an internalcombustion engine in the fuel tank normally provided with the vehicle orother device powered by such engine. The system includes a heatexchanger which is installed in the fuel tank of the vehicle or otherdevice. In the preferred embodiment, the heat exchanger is installedthrough and secured to the opening normally provided in the fuel tanksof most diesel engine-powered over-the-road trucks for installation of afuel gauge. Most such trucks are provided with two fuel tanks and thefuel gauge access opening is usually only used for a fuel gauge in oneof the tanks. Therefore the unused opening in one of the tanks can beused for installation of the present invention.

In the preferred embodiment, the heat exchanger is an elongatedsubstantially cylindrically shaped device made of a thermally conductivematerial, preferably a corrosion resistant metal. The heat exchangerincludes a heated fluid chamber and a fuel tube extending through suchchamber. The heated fluid chamber includes an inlet port and an outletport positioned in a first end portion of the heat exchanger. A dividerplate is provided in the heated fluid chamber between the inlet andoutlet port which extends from the first end portion of the chamberthrough all but a small portion of the length of the chamber. Thedivider plate divides the heated fluid chamber into an inlet section andan outlet section whereby heated fluid from an external source entersthrough the inlet port and travels through the inlet section toward thesecond end portion of the chamber where it passes into the outletsection and travels back toward the first end portion where it exitsthrough the outlet port and is returned to the external source forreheating. Heat is transferred through the external walls of the heatexchanger from the heated fluid to the fuel in the fuel tank.

As indicated above, a fuel tube is provided which extends through, andis therefore surrounded by the heated fluid chamber. In the preferredembodiment, fuel is drawn into an open fuel inlet end of the tubeproximate and external to the second end portion of the heat exchangerand is drawn through the fuel tube where it is further heated by theheated fluid in the above-described chamber which surrounds the fueltube and exits from the fuel outlet end of the tube which is connectedto the fuel line of the vehicle in which the present invention isinstalled, proximate and external to the first end portion of the heatexchanger.

In the preferred embodiment, the external source of heated fluid is theradiator of the vehicle in which the present invention is installed.Fluid communication can be provided between the radiator and the inletand outlet ports of the above-described heated fluid chamber viaflexible hoses similar to those normally used in internal combustionengines to provide fluid communication between the radiator and theengine block. In another embodiment of the present invention, the heatedfluid can comprise lubricating oil circulated from the oil pan of theengine with which the system is used.

Fuel is drawn from the fuel tank through the fuel tube of the presentinvention into the fuel line as described above by the fuel pump of theengine of the vehicle or other device in which the system is installed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a perspective view, partially cut away of a systemfor preheating fuel for an internal combustion engine in a fuel tankconstructed in accordance with various features of the presentinvention.

FIG. 2 illustrates a top view in section of the heat exchanger, taken at2--2 of FIG. 1, of a system for preheating fuel for an internalcombustion engine constructed in accordance with various features of thepresent invention.

FIG. 3 illustrates a front elevation view of an alternate embodiment ofa system for preheating fuel for an internal combustion engine in a fueltank constructed in accordance with various features of the presentinvention.

FIG. 4 illustrates a block diagram of a system for preheating fuel foran internal combustion engine in a fuel tank constructed in accordancewith various features of the present invention as illustrated in FIGS. 1and 2.

FIG. 5 illustrates a perspective view, partially cut away, of anotherembodiment of a system for preheating fuel for an internal combustionengine in accordance with various features of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

A system for preheating fuel for an internal combustion engine in thefuel tank normally provided with the vehicle or other device powered bysuch engine is illustrated generally at 10 in FIG. 1. The systemincludes a heat exchanger shown generally at 12 in FIG. 1. The heatexchanger 12 is installed through an access opening 14 which is normallyprovided in fuel tanks for diesel engine-powered over-the-road trucksfor installation of a fuel gauge. A portion of such a fuel tank isillustrated at 16 in FIG. 1. The heat exchanger 12 is provided with aflange 18, which is dimensioned and predrilled to match the flange 20surrounding the opening 14 in the fuel tank 16, proximate a first endportion 22 of the heat exchanger 12. When the system 10 is installed, anappropriate gasket or seal (not shown) is installed between the flange18 and the flange 20.

The heat exchanger 12 comprises a substantially cylindrical vesselhaving an outer wall 24 which defines an interior heated fluid chamber26. An inlet port 28 and an outlet port 30 are provided proximate thefirst end portion 22 of the heat exchanger 12, between the first endportion 22 and the flange 18, through which a heated fluid is suppliedfrom and returned to an external source of the heated fluid. A fuel tube32 extends axially through the heat exchanger 12 from externally of itssecond end portion 34 to externally of its first end portion 22. Thefuel tube 32 is surrounded by the heated fluid chamber 26 as shown inFIGS. 1 and 2. The heated fluid chamber 26 is divided into an inletsection 36 and an outlet section 38, as illustrated in FIG. 2, by adivider plate 40, comprised of two coplanar plate sections 40A and 40Bpositioned between the fuel tube 32 and the outer wall 24 of the heatexchanger 12. The divider plate 40 extends from the first end portion 22of the heat exchanger 12, parallel to the fuel tube 32, for all but asmall portion of the length of the heat exchanger 12 where it terminatesin a distal end portion 42, such that fluid communication is providedbetween the inlet section 36 and the outlet section 38 of the heatedfluid chamber 26 proximate the second end portion 34 of the heatexchanger.

Referring to FIG. 1 and to FIG. 4, which is a block diagram of thesystem 10, it can be seen that heated fluid enters via an appropriatefitting 44 into the inlet port 28 of the heat exchanger 12, as indicatedby the arrows 50A and 50B. The heated fluid travels down through theinlet section 36 of the heated fluid chamber 26 and under the distal endportion 42 of the divider plate 40 into the outlet section 38 of theheated fluid chamber 26, as indicated by the arrows 50B, 50C, and 50D.The heated fluid exits the outlet section 38 of the chamber 26 throughthe outlet port 30 via an appropriate fitting 46, as indicated by thearrows 50E and 50F. It will be appreciated by those skilled in the artthat heat from the heated fluid will be transferred to the fuel in thefuel tank which surrounds the heat exchanger 12, which preferably isconstructed of a corrosion resistant metal which has good thermalconductivity. In the preferred embodiment, the heated fluid comprisesheated coolant supplied from and returned to the radiator of the vehicleor other device in which the system 10 is installed as illustrated bythe block diagram illustrated by FIG. 4. It will be appreciated by thoseskilled in the art that fluid communication can be provided between theradiator and the inlet and outlet port fittings, 44 and 46 respectively,by hoses, indicated by the reference numerals 52A and 52B in FIG. 4,similar to those typically used between a radiator and the block of aninternal combustion engine.

Also, as indicated with dashed lines in FIG. 4, the hoses 52A and 52Bcould be alternately connected to the oil pan of the internal combustionengine for the circulation of lubricating oil as the heated fluid forthe heating of the fuel.

Still referring to FIGS. 1 and 4, it can be seen that fuel from the fueltank enters the fuel tube 32 through the open fuel inlet end 48 of thetube 32, as indicated by the arrow 60A, and exits through the fueloutlet end 54 of the tube 32, proximate and externally of the first endportion 2 of the heat exchanger 12, as indicated by the arrow 60B. Theoutlet end 54 of the fuel tube 32 communicates with the fuel line,indicated by the line 60 in the block diagram illustrated in FIG. 4,which supplies fuel to the engine. It will be appreciated by thoseskilled in the art that the fuel entering the fuel line will have beenfurther heated in the fuel tube 32 by the heated fluid in the chamber 26which surrounds the tube 32.

Referring to FIG. 3, an alternate embodiment 10' of the system of thepresent invention is illustrated. In the system 10', the heat exchanger12' comprises a U-shaped tube secured proximate its inlet and outletopenings, 28' and 30', respectively, to a flange 18' which may besecured to a fuel tank 16 in a manner similar to that described for thesystem 10 illustrated in FIGS. 1, 2 and 4.

Referring now to FIG. 5, another alternate embodiment 10" of the systemof the present invention is illustrated. In the system 10", the heatexchanger 12" comprises an elongated substantially cylindrical vesselhaving a similar overall external appearance to the heat exchanger 12 ofthe system 10 illustrated in FIG. 1. However, in this embodiment, thereis no fuel tube extending through the heat exchanger 12" as in thesystem 10; in this system 10", fuel is drawn from the bottom of the fueltank in the conventional manner, i.e. fuel line connections in thevehicle or other device in which the system is used are leftundisturbed. The heat exchanger 12" defines a heated fluid chamber 26"and includes a heated fluid inlet port 28" coaxially (with thelongitudinal axis of the heat exchanger 12") positioned in the first endportion 22" of the heat exchanger. A heated fluid inlet tube 70 isprovided which extends coaxially through the heat exchanger 12" from aninlet end 72, positioned externally of and proximate the first endportion 22" of the heat exchanger 12", through the inlet port 28", to anopen outlet end 74 positioned within the heated fluid chamber 26"proximate the second end portion 34" of the heat exchanger, such thatheated fluid in the inlet tube 70 flows into the heated fluid chamber26", as indicated by the arrows 50". In this embodiment, heated fluidfrom an external source (as described above for the system 10) entersthe inlet end 72 of the inlet tube 70, flows down through the tube 70and out of the outlet end 74 into the chamber 26" proximate the secondend portion 34" of the heat exchanger 12", and back toward the first endportion 22" of the heat exchanger where it exits through the outlet port30", as indicated by the arrows 50A", 50" and 50B". The heat exchanger12" includes a flange 18" which may be secured to a fuel tank 16 in amanner similar to that described for the system 10 illustrated inFIG. 1. It will be appreciated by those skilled in the art that, becauseof the flow path of the heated fluid, the greatest heat transfer fromthe heated fluid to the fuel in the fuel tank will occur near the secondend portion 34" of the heat exchanger 12". Since the heat exchanger isinstalled through an opening normally provided in the top portion of thefuel tank, the second end portion 34" of the heat exchanger will bepositioned near the bottom of the fuel tank from which fuel is drawninto the fuel line. Therefore, heating of the fuel entering the fuelline is enhanced. This embodiment of the present invention also has theadvantage of having improved heat transfer characteristics over priorart systems which utilize a U-shaped tube heat exchanger similar to thatshown in the system 10' illustrated in FIG. 3. Heat transfer from theheated fluid to the fuel in the fuel tank is increased because of therelatively large surface area provided by the external walls 24 of theheat exchanger 12" as compared to the U-shaped tube devices.

In light of the foregoing, it can be seen that a system 10 is providedby the present invention for preheating the fuel for an internalcombustion engine in the fuel tank 16 by a heat exchanger 12 installedthrough an access opening 14 in the fuel tank. Heat from a heated fluidwhich is supplied to the heat exchanger 12, as indicated by the arrows50, is transferred to the fuel in the fuel tank 16. The fuel is furtherheated by the heated fluid as it is drawn through the fuel tube 32 intothe fuel line 60. Accordingly, when the system 10 is installed in avehicle or other device powered by an internal combustion engine, theefficiency of such engine will be improved. In particular, the system 10will eliminate or minimize the problem of congealing or "waxing" ofdiesel fuel in a diesel engine-powered vehicle or other device operatedin cold weather environments.

While a preferred embodiment has been shown and described, it will beunderstood that it is not intended to limit the invention to suchdisclosure, but rather it is intended to cover all modifications andalternate constructions falling within the scope of the invention asdefined in the appended claims.

I claim:
 1. A system for preheating fuel for an internal combustionengine having a fuel line comprising:a fuel tank for storing fuel to besupplied to said fuel line, said tank having an access opening providedin an upper portion thereof; an elongated heat exchanger installedthrough and secured to said access opening, a substantial portion ofsaid heat exchanger being contained within said fuel tank; said heatexchanger defining an inlet port and an outlet port proximate a firstend portion of said heat exchanger positioned externally of said fueltank; a heated fluid chamber defined by said heat exchangercommunicating between said inlet and outlet ports, said heated fluidchamber including a divider plate which separates said heated fluidchamber into an inlet section communicating with said inlet port and anoutlet section communicating with said outlet port, said divider platebeing positioned such that a heated fluid entering said inlet port flowstoward a second end portion of said heat exchanger where said heatedfluid flows through said outlet section of said heated fluid chamber andexists through said outlet port; a source of said heated fluid; meansfor providing fluid communication between said source of heated fluidand said inlet and outlet ports of said heat exchanger; said heatexchanger further comprising a fuel tube passing substantially axiallythrough said heated fluid chamber and forming a portion of said dividerplate, said fuel tube having a fuel inlet end positioned externally ofsaid heated fluid chamber proximate said second end portion of said heatexchanger in fluid communication with said fuel in said fuel tank, andsaid fuel tube having a fuel outlet end positioned externally of saidheated fluid chamber proximate said first end portion of said heatexchanger in fluid communication with said fuel line of said internalcombustion engine; whereby said fuel in said fuel tank is heated by heattransferred from heated fluid contained within said heated fluid chamberthrough the walls of said heat exchanger; and whereby fuel drawn fromsaid fuel tank through said fuel tube into said fuel line is furtherheated by heat transferred from heated fluid contained by said heatedfluid chamber which surrounds said fuel tube.
 2. The system of claim 1wherein said source of heated fluid comprises a radiator containing acoolant which communicates with a block of said internal combustionengine for cooling said engine.
 3. The system of claim 1 wherein saidsource of heated fluid comprises an oil pan of said internal combustionengine.
 4. A system for preheating fuel for an internal combustionengine of a vehicle having a fuel line, said vehicle being equipped witha fuel tank for storing fuel to be supplied to said fuel line, said fueltank provided with an access opening in an upper portion thereof, whichcomprises:an elongated shell member defining an exterior surface of aheat exchanger, said shell member installed through and secured to saidaccess opening with a first substantial portion of said shell memberdisposed within said fuel tank and a second portion disposed exteriorsaid fuel tank, said shell member provided with an inlet port and anoutlet port in said second portion exterior said fuel tank, said shellmember having a lengthwise axis; a top closure for said second portionof said shell member exterior to said fuel tank; a bottom closure forsaid first portion of said shell member; a fuel tube mounted axiallywithin said shell member, said fuel tube extending through and sealed tosaid top and bottom closures of said shell member, said fuel tube havingan open first end proximate said bottom closure, said open first endhaving communication with said fuel tank, and an open second endproximate said top closure for connection with said fuel line; a pair ofoppositely disposed divider plates disposed axially within said shellmember extending from said top closure to a distal end positioned nearsaid bottom closure, said divider plates attached to and extendingradially to said fuel tube and further attached to said top closure,said divider plates forming an inlet portion within said shell membercommunicating with said inlet port and an outlet portion within saidshell member communicating with said outlet port, said inlet portion andsaid outlet portion joined at said distal end of said divider plates; asource of heated fluid; and means for providing fluid communicationbetween said source of heated fluid and said inlet and outlet ports ofsaid shell member whereby said heated fluid flows into said shell memberthrough said inlet port into said inlet portion, through said outletportion and out through said outlet port to thereby transfer heat fromsaid heated fluid to fuel in said fuel tank, and whereby said heatedfluid flowing through said shell member transfers heat into fuel flowingthrough said fuel tube from said fuel tank to said fuel line.
 5. Thesystem of claim 4 wherein said source of heated fluid comprises aradiator containing a coolant which communicates with a block of saidinternal combustion engine for cooling said engine.
 6. The system ofclaim 4 wherein said source of heated fluid comprises an oil pan of saidinternal combustion engine.